Outline
https://www.getoutline.com/: "Open source wiki and knowledge base for growing teams" - rich text editor that transforms markdown on the fly. Free for up to 5, paid hosting or self-hosted, uses Slack or Google for logins. Full markdown export.
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Blot.im
https://blot.im/: "A blogging platform with no interface". Specifically, it uses your own Dropbox account to create the files that it transforms into a blog for you. For $20 / year, this is pretty awesome.
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